//
//  ffmpeg-audio-sdl12.c
//  FFMPEG-Serial-Demo
//
//  Created by aron on 2018/1/4.
//  Copyright © 2018年 aron. All rights reserved.
//

#include "ffmpeg-audio-sdl12.h"

//
//FFMPEG+SDL音频解码程序
//雷霄骅
//中国传媒大学/数字电视技术
//leixiaohua1020@126.com
//
//
#include <stdlib.h>
#include <string.h>
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswresample/swresample.h" // other linker flags: -lswresample
//SDL
#include "SDL/SDL.h"
#include "SDL/SDL_thread.h"
//#include "decoder.h"
//#include "wave.h"

//#define _WAVE_

//全局变量---------------------
static  Uint8  *audio_chunk;
static  Uint32  audio_len;
static  Uint8  *audio_pos;
//-----------------
/*  The audio function callback takes the following parameters:
 stream: A pointer to the audio buffer to be filled
 len: The length (in bytes) of the audio buffer (这是固定的4096？)
 回调函数
 注意：mp3为什么播放不顺畅？
 len=4096;audio_len=4608;两个相差512！为了这512，还得再调用一次回调函数。。。
 m4a,aac就不存在此问题(都是4096)！
 */
void  fill_audio(void *udata,Uint8 *stream,int len){
    /*  Only  play  if  we  have  data  left  */
    if(audio_len==0)
        return;
    /*  Mix  as  much  data  as  possible  */
    len=(len>audio_len?audio_len:len);
    SDL_MixAudio(stream,audio_pos,len,SDL_MIX_MAXVOLUME);
    audio_pos += len;
    audio_len -= len;
}
//-----------------


int decode_audio(char* no_use)
{
    AVFormatContext    *pFormatCtx;
    int                i, audioStream;
    AVCodecContext    *pCodecCtx;
    AVCodec            *pCodec;
    
    char url[300]={0};
    strcpy(url, no_use);
    //Register all available file formats and codecs
    av_register_all();
    
    //支持网络流输入
    avformat_network_init();
    //初始化
    pFormatCtx = avformat_alloc_context();
    //有参数avdic
    //if(avformat_open_input(&pFormatCtx,url,NULL,&avdic)!=0){
    if(avformat_open_input(&pFormatCtx,url,NULL,NULL)!=0){
        printf("Couldn't open file.\n");
        return -1;
    }
    
    // Retrieve stream information
    if(avformat_find_stream_info(pFormatCtx, NULL)<0)
    {
        printf("Couldn't find stream information.\n");
        return -1;
    }
    
    // Dump valid information onto standard error
    av_dump_format(pFormatCtx, 0, url, 0);
    
    // Find the first audio stream
    audioStream=-1;
    for(i=0; i < pFormatCtx->nb_streams; i++) {
        //原为codec_type==CODEC_TYPE_AUDIO
        if(pFormatCtx->streams[i]->codecpar->codec_type==AVMEDIA_TYPE_AUDIO)
        {
            audioStream=i;
            break;
        }
    }
    
    if(audioStream==-1)
    {
        printf("Didn't find a audio stream.\n");
        return -1;
    }
    
    // Get a pointer to the codec context for the audio stream
    pCodecCtx=pFormatCtx->streams[audioStream]->codec;
    
    // Find the decoder for the audio stream
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
    if(pCodec==NULL)
    {
        printf("Codec not found.\n");
        return -1;
    }
    
    // Open codec
    if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
    {
        printf("Could not open codec.\n");
        return -1;
    }
    
    /********* For output file ******************/
    FILE *pFile;
#ifdef _WAVE_
    pFile=fopen("output.wav", "wb");
    fseek(pFile, 44, SEEK_SET); //预留文件头的位置
#else
    pFile=fopen("output.pcm", "wb");
#endif
    
    // Open the time stamp file
    FILE *pTSFile;
    pTSFile=fopen("audio_time_stamp.txt", "wb");
    if(pTSFile==NULL)
    {
        printf("Could not open output file.\n");
        return -1;
    }
    fprintf(pTSFile, "Time Base: %d/%d\n", pCodecCtx->time_base.num, pCodecCtx->time_base.den);
    
    /*** Write audio into file ******/
    //把结构体改为指针
    AVPacket *packet=(AVPacket *)malloc(sizeof(AVPacket));
    av_init_packet(packet);
    
    //音频和视频解码更加统一！
    //新加
    AVFrame    *pFrame;
    pFrame=av_frame_alloc();
    //输出音频数据大小，一定小于输出内存。
    int out_linesize;
    //输出内存大小
    int out_buffer_size=av_samples_get_buffer_size(&out_linesize, pCodecCtx->channels,pCodecCtx->frame_size,pCodecCtx->sample_fmt, 1);
    uint8_t *out_buffer=malloc(out_buffer_size * sizeof(uint8_t));
    //---------SDL--------------------------------------
    //初始化
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        printf( "Could not initialize SDL - %s\n", SDL_GetError());
        exit(1);
    }
    
    //结构体，包含PCM数据的相关信息
    SDL_AudioSpec wanted_spec;
    wanted_spec.freq = pCodecCtx->sample_rate;
    wanted_spec.format = AUDIO_S16SYS;
    wanted_spec.channels = pCodecCtx->channels;
    wanted_spec.silence = 0;
    wanted_spec.samples = 1024; //播放AAC，M4a，缓冲区的大小
    //wanted_spec.samples = 1152; //播放MP3，WMA时候用
    wanted_spec.callback = fill_audio;
    wanted_spec.userdata = pCodecCtx;
    
    if (SDL_OpenAudio(&wanted_spec, NULL)<0)//步骤（2）打开音频设备
    {
        printf("can't open audio.\n");
        return 0;
    }
    //-----------------------------------------------------
    printf("比特率 %3d\n", (int)pFormatCtx->bit_rate);
    printf("解码器名称 %s\n", pCodecCtx->codec->long_name);
    printf("time_base  den:%d  num:%d\n", pCodecCtx->time_base.den, pCodecCtx->time_base.num);
    printf("声道数  %d \n", pCodecCtx->channels);
    printf("sample per second  %d \n", pCodecCtx->sample_rate);
    //新版不再需要
    //    short decompressed_audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];
    //    int decompressed_audio_buf_size;
    int ret, len = 0;
    int got_picture;
    int index = 0;
    struct SwrContext *au_convert_ctx;
    au_convert_ctx = swr_alloc();
    au_convert_ctx=swr_alloc_set_opts(au_convert_ctx,AV_CH_LAYOUT_STEREO, AV_SAMPLE_FMT_S16, 44100,
                                      pCodecCtx->channel_layout,pCodecCtx->sample_fmt , pCodecCtx->sample_rate,0, NULL);
    swr_init(au_convert_ctx);
    while(av_read_frame(pFormatCtx, packet)>=0)
    {
        if(packet->stream_index==audioStream)
        {
            //decompressed_audio_buf_size = (AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2;
            //原为avcodec_decode_audio2
            //ret = avcodec_decode_audio4( pCodecCtx, decompressed_audio_buf,
            //&decompressed_audio_buf_size, packet.data, packet.size );
            //改为
            ret = avcodec_decode_audio4( pCodecCtx, pFrame,
                                        &got_picture, packet);
            if ( ret < 0 ) // if error len = -1
            {
                printf("Error in decoding audio frame.\n");
                exit(0);
            }
            if ( got_picture > 0 )
            {
#if 1
                swr_convert(au_convert_ctx, &out_buffer, out_linesize, (const uint8_t **)pFrame->data , pFrame->nb_samples);
                printf("index:%5d\t pts %5d\n", index, (int)packet->pts);
#endif
                
#if 1
                printf("index %3d\n", index);
                printf("pts %5d\n", (int)packet->pts);
                printf("dts %5d\n", (int)packet->dts);
                printf("packet_size %5d\n", packet->size);
                
                //printf("test %s\n", rtmp->m_inChunkSize);
#endif
                //直接写入
                //注意：数据是data【0】，长度是linesize【0】
#if 1
                fwrite(out_buffer, 1, out_linesize, pFile);
                //fwrite(pFrame, 1, got_picture, pFile);
                //len+=got_picture;
                //fprintf(pTSFile, "%4d,%5d,%8d\n", index, decompressed_audio_buf_size, packet.pts);
#endif
                index++;
            }
#if 1
            //---------------------------------------
            //printf("begin....\n");
            //设置音频数据缓冲,PCM数据
            audio_chunk = (Uint8 *) out_buffer;
            //设置音频数据长度
            audio_len = out_linesize;
            //audio_len = 4096;
            //播放mp3的时候改为audio_len = 4096
            //则会比较流畅，但是声音会变调！MP3一帧长度4608
            //使用一次回调函数（4096字节缓冲）播放不完，所以还要使用一次回调函数，导致播放缓慢。。。
            //设置初始播放位置
            audio_pos = audio_chunk;
            //回放音频数据
            SDL_PauseAudio(0);
            //printf("don't close, audio playing...\n");
            while(audio_len>0)//等待直到音频数据播放完毕!
                SDL_Delay(1);
            //---------------------------------------
#endif
        }
        // Free the packet that was allocated by av_read_frame
        //已改
        av_packet_unref(packet);
    }
    //printf("The length of PCM data is %d bytes.\n", len);
    
#ifdef _WAVE_
    fseek(pFile, 0, SEEK_SET);
    struct WAVE_HEADER wh;
    
    memcpy(wh.header.RiffID, "RIFF", 4);
    wh.header.RiffSize = 36 + len;
    memcpy(wh.header.RiffFormat, "WAVE", 4);
    
    memcpy(wh.format.FmtID, "fmt ", 4);
    wh.format.FmtSize = 16;
    wh.format.wavFormat.FormatTag = 1;
    wh.format.wavFormat.Channels = pCodecCtx->channels;
    wh.format.wavFormat.SamplesRate = pCodecCtx->sample_rate;
    wh.format.wavFormat.BitsPerSample = 16;
    calformat(wh.format.wavFormat); //Calculate AvgBytesRate and BlockAlign
    
    memcpy(wh.data.DataID, "data", 4);
    wh.data.DataSize = len;
    
    fwrite(&wh, 1, sizeof(wh), pFile);
#endif
    SDL_CloseAudio();//关闭音频设备
    // Close file
    fclose(pFile);
    // Close the codec
    avcodec_close(pCodecCtx);
    // Close the video file
    avformat_close_input(&pFormatCtx);
    
    return 0;
}

